Sell photos.
If you have a decent camera and a good sense of light, color, and
composition, you can take and sell stock photos – i.e. nondescript
images that lend themselves to many applications and are commonly used
to illustrate online articles or products – with minimal effort. Stock
photos of locations (a fire hydrant, a bare wall near an interesting
tree, or anything you might find as a default background image on your
computer) are easier to take, but stock photos of people (i.e. people
arguing, people kissing, people laughing) usually sell for more, as they
have more uses and require the written legal consent of your subjects.
Hunt for a reputable stock photo dealer or database that will pay you
fairly before signing on with anyone.